The present invention relates to an apparatus and method for forming a thin film to be used in semiconductor devices or liquid crystal panels, etc. and an apparatus and method for forming a film and pattern-etching to obtain the desired thin films, that is particularly designed to improve the yield.
With the remarkable progress of semiconductor devices toward high-density and a highly integrated structure, the devices become more and more finely constructed in complicate arrangements fully utilizing multi-layered wiring technology.
Conventionally, BPSG films, SiO.sub.2 films, PSG films, NSG films, or SiON films obtained through atmospheric pressure CVD, low pressure CVD, or plasma CVD are often used as interlayer dielectrics. Or, a liquid glass agent applied on a substrate with a metallic wiring is set up through thermal treatment to thereby obtain an interlayer dielectric film.
One example of a conventional thin film forming apparatus will be described with reference to FIG. 10.
FIG. 10 illustrates the structure of a conventional atmospheric pressure CVD apparatus employed in a manufacturing process of semiconductors. In FIG. 10, a substrate 1 set on a transfer holder 2 is sent to a lamp heating chamber 4 while it is supported on a conveyor 3 driven by a driving means (not shown). The ambience in the chamber 4 is controlled by an inert gas such as nitrogen gas or the like. The substrate 1, preliminarily heated in the lamp heating chamber 4, is sent to an atmospheric CVD film forming chamber 5. In the film forming chamber 5, the substrate 1 is kept at a predetermined temperature by a heater 6 via the transfer holder 2 in order to react at the surface thereof with a reaction gas introduced into the chamber 5 through a gas nozzle 7. At this time, while a predetermined pressure is impressed on the reaction gas by a pressure control means (not shown), the reaction gas is discharged from a discharge port 8. As a result, a desired BPSG film or an SiO.sub.2 film is formed. The reaction gas for the BPSG film is a mixture of silane (represented as SiH.sub.4 hereinbelow), oxygen (represented by O.sub.2 hereinafter), phosphine (PH.sub.3), and diborane (B.sub.2 H.sub.6). On the other hand, the reaction gas for the SiO.sub.2 film is mixture of tetraethoxysilane (TEOS) and ozone (O.sub.3). The substrate 1 on which the above film is formed is then sent into a cooling chamber 9 by the holder 2 and the conveyor 3, and cooled to a predetermined temperature in a nitrogen atmosphere. Thereafter, the substrate is separated from the holder 2 by a carry-out arm 10 and stored in a substrate cassette 11.
In general, the aforementioned BPSG films, SiO.sub.2 films, PSG films, NSG films, SION films, etc. have high hygroscopic properties. Therefore, the films absorb moisture over time, resulting in dust on the surface thereof or inviting a deterioration of their insulating properties.
Moreover, if a metallic wiring pattern, a semiconductor film pattern, or an insulating film pattern is also present on the surface of the substrate, the forming speed of the films or the quality of the films may differ depending on the differences of the surface properties of the films.
In the prior art, therefore, the thin BPSG films absorbing moisture cannot be avoided while the substrate 1 with the film is stored in the substrate cassette 11 or the substrate 1 is carried and transferred to a next process, resulting in the reaction of B and P in the film, with dust generated on the surface of the substrate 1 or the insulation of the film being deteriorated. That is, the quality of the films cannot be maintained to be constant and stable and the yield is poor.
In the case where the surface of the substrate, before the film is formed thereon by an atmospheric pressure CVD apparatus, is not coated with a layer of single quality, e.g., if a metallic wiring pattern, a semiconductor film pattern, or an insulating film pattern is intermingled, the thickness or the quality of the SiO.sub.2 film cannot be uniformly secured due to the dependency on the undercoat, and the yield is lowered.